The invention relates generally to the field of gene therapy. A variety of methods have been described in the literature as being useful for delivering a desired molecule into a target cell. The combined use of 1) complete vascular isolation using tourniquets and proximal arterio-venous cannulation, 2) systemic heparinization to prevent thrombosis, 3) peripheral vasodilation to optimize perfusion of muscle capillaries, and 4) histamine to produce physical gaps between adjacent endothelial cells has achieved widespread, homogeneous, vector-independent gene transfer to muscles of entire extremities. These studies began with marker genes and were then applied to several disease models in larger rodents and dogs. However, the four essential components of the protocol listed above have stymied clinical translation because of the inherent risk of hemorrhage, hypotension, and pulmonary dysfunction.
For example, U.S. Pat. No. 6,177,403 describes a kit for delivering a macromolecular assembly to the extravascular tissue of an animal. This kit involves the use of a vascular permeability-enhancing agent and a vasodilating agent. However, such agents can be associated with undesirable side effects, including short-term toxicity, which minimizes the usefulness of such methods.
Systems for pressure mediated selective delivery of therapeutic substances to specific areas of organs and cannula useful therein have been described. See, e.g., WO 99/59666, Nov. 25, 1999. However, these methods and devices avoid systemic delivery of therapeutic substances.
Further, studies in large animal models have revealed a trade-off between the efficiency of gene transfer using known methods and the inherent safety of the required pharmacological interventions.
What are needed are methods that facilitate delivery of target molecules to the desired host cell while minimizing side effects.